Real Estate - Disposed Properties to Unaffiliated Parties (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) Property ApartmentUnit	Dec. 31, 2019 USD ($) Property ApartmentUnit
Properties disposed | Property	6	13
Property Units disposed | ApartmentUnit	2,231	3,306
Sales Price	$ 1,122,371	$ 1,477,275
Rental Properties – Consolidated [Member]
Properties disposed | Property	6	11
Property Units disposed | ApartmentUnit	2,231	2,361
Sales Price	$ 1,066,861	$ 1,080,675
Rental Properties – Unconsolidated [Member]
Properties disposed | Property		2
Property Units disposed | ApartmentUnit		945
Sales Price		$ 394,500
Land Parcels [Member]
Sales Price	$ 55,510	$ 2,100